XAMPP is a completely free, easy to install Apache distribution containing MariaDB, PHP, and Perl.
BitNami Stacks make it incredibly easy to deploy your favorite open source software. BitNami Stacks include an open source application and all of the other software necessary to run it, such as Apache, MySQL, PHP or Ruby.
MAMP installs a local server environment in a matter of seconds on your computer. It comes free of charge, and is easily installed. MAMP will not compromise any existing Apache installation already running on your system.
InstantWP is a complete standalone, portable WordPress development environment. It will turn almost any Windows or macOS machine into a WordPress development server. It will even run from a USB key.
No release since 2018. The developer doesn't seem to answer bug reports and issues on GitHub anymore, and the used port (10080) is now blocked by default on modern browsers (see https://github.com/webtoolsgroup/InstantWP/issues/103).
WordPress Portable is a free program for Windows that automatically ships with everything needed to run WordPress locally. All you need to do is to extract the package contents on your system after download and start the WordPress Portable executable afterwards.
The project is no longer developed. Last version, 3.5, can be still downloaded from the Box link on the official website